A Low-Investment Option for the Integrated Semi-mechanized Harvesting of Small-Scale, Short-Rotation Poplar Plantations

In recent years, industrial roundwood production has enjoyed a steady success due to the development of a new bioeconomy and the rapid structural changes of the wood market. A very promising new solution for industrial fiber crops is the integrated production of logs and biomass in short rotation poplar plantations. In Europe, the expansion of these crops is concentrated in the Eastern regions, where contractors face strict limitations in their capital availability: hence the interest in developing semi-mechanized, low-investment harvesting systems based on general-purpose equipment that may serve as a stop-gap solution to assist the transition to fully mechanized systems. This study focused on designing and testing such a system, based on two low-cost machines (an excavator with a grapple saw and a second-hand forwarder) and requiring a minimum workforce (two operators only). The system was tested for productivity, cost and work quality, under two variants: production of 2 or 4 m logs. This system can produce approximately 3 loads (90 t) per day, at a cost between 14.5 and 16 EUR t-1, from stump to roadside landing, ready for loading and transportation. The 4 m log variant was more efficient, resulting in a 10% cost reduction around 1.5 EUR t-1. However, log yield was relatively low: between 1/3 and 1/4 of the total harvest, the balance consisting of lower-value biomass. The 2 m log treatment offered a higher log yield. The introduction of simple technology may allow increasing log yield and should be the subject of future research.